Ignazio Marino was a "distinctive sight" commuting to and from his his job as a transplant surgeon at Thomas Jefferson University Hospital in Philadelphia via red Schwinn. "Even though Marino spent his formative years in cities whose narrow streets encourage walking - Genoa as a child, Rome for medical school - he said it wasn't until he moved to Philadelphia in 2003 that he lived in a city without owning a car," writes Inga Saffron.

When he began campaigning to become the mayor of Rome on promises to "make the car-choked Italian capital a more livable place," it was those experiences in Philadelphia that informed his agenda.

"Unlike Parisians, who have taken to their Velib bike-share system with a vengeance, or Londoners, who have pedestrianized part of Trafalgar Square, he felt Romans had been slow to adopt planning ideas that favor walkers and bicyclists - even though they practically invented the gracious pedestrian plaza."

After closing one central Roman road to nonessential traffic on weekdays and all motorized vehicles on weekends, Marino is looking to add more car-free zones, launch a bike-share program, and expand the city's network of bike lanes.